Metaphysics. This is a tough question, depends greatly on your equipment.
In my system, there is no doubt LP outperforms both CD and SACD. However, this should not come as any surprise, considering my analog equipment is valued at about thirty five times what my SACD format is.
The Miles Davis 45 RPM set at $150. reflects the fact it is out of print. I consider this a heavy investment, considering the original sales price a few months ago. The original Columbia version of "Kind of Blue" Still outperforms the SACD and CD versions, and the two audiophile releases in both 33 and 45, perform equal or above the original, depending on the pressing. Again, this is with my system, and comparing against my Sony S9000 ES SACD player. As SACD software and playback equipment continues to evolve, the results could certainly reverse.
As for worrying about your investment in vinyl, the rare items will continue to retain, and perhaps gain value for many years to come. I would be more concerned with investing too heavily in SACD software, particularly if you are duplicating titles. Sony is bound to offer lower prices in the near future to promote the format. When this happens, your (and mine) existing SACD software will certainly drop in value.
CD's will probably remain on their same course for a long time, there are so many titles and so many players, I would expect it to remain strong for at least for another ten years. After all, my brand new car came equipped with both CD and a cassette player. How long has it been since any of us considered the cassette the top format?